Figure 1. (a): Time series of the number of tropical cyclones in the
Australian region (105°-165° E) between 1969 to 1995. Dark bars indicate the
number of cyclones with minimum
pressure below 990 hPa. The grey bars indicate the numbers with minimum
pressure between
1000 and 990 hPa (adapted from Nicholls et al. 1997). (b): Time series of
Atlantic basin
intense hurricanes (dark bars) and weaker cyclones (grey bars) for
1944-1995. Intense
hurricanes are those cyclones that attain sustained surface winds of at
least 50 ms-1 at some
point in their life cycle. Weaker cyclones include all other remaining
tropical storms,
subtropical storms, and hurricanes. The superimposed lines are the linear
best fits for the
intense hurricanes (lower line) and for the total number of cyclones (upper
line) (from Landsea
et al. 1996).